The Error Reporting page documents the differences between error API V1 and V2, including a table of the error domain in V1 and corresponding error domain in V2.

The paragraph says:

The driver’s error reporting began with a design flaw: when the error domain is MONGOC_ERROR_COLLECTION, MONGOC_ERROR_QUERY, or MONGOC_ERROR_COMMAND, the error code might originate from the server or the driver.

But the table does not have an entry for MONGOC_ERROR_COLLECTION. I think that is either missing, or the row for mongoc_collection_insert_one() and the other collection write functions is incorrectly documented.